1. Field of the Invention
This invention relates to the testing of semiconductor memory devices utilizing special purpose computer programs.
2. Description of the Prior Art
The use of special purpose computers in the testing of semiconductor memory devices is well known in the prior art. Certain prior art techniques require that each bit of the memory be tested with the most complex test patterns representative of the most complex conditions to be encountered in operation, as well as the simplest, in order to insure that the memory device will function properly in a system. Typically, several tests are performed where, in a predetermined pattern of ones and zeroes, a single bit is altered, and then all bits in the memory are reverified. Such tests are performed until each bit is changed several times, with the entire memory array being reverified after each change. Thus, there must be a minimum of N.sup.2 T bit verifications performed, where N is the number of bits in the memory, and T is the number of times each bit is changed.
Thus, testing time increases as the square of the number of bits in the memory. For very large memories, this testing time may become several hours per device, which would be prohibitively expensive.